Project Summary DESCRIPTION (provided by applicant): The purpose of the proposed Mentored Scientist Career Development Award (K01) is to prepare the candidate with competencies to become an independent NIH-funded researcher. The candidate?s long-term goal is to develop expertise in HIV prevention research and in community-level HIV prevention design, implementation, and evaluation. The proposed research in the K01 period is to investigate the role of community-level mechanisms linking social capital to late HIV diagnosis in the United States (US). Late HIV diagnosis remains a persistent public health threat in the US; it is associated with poorer survival among HIV+ persons, and drives onward HIV transmission in the community. The association among social capital, mediating mechanisms and HIV diagnosis remains under-investigated in the US. Aim 1: To characterize the longitudinal relationship between social capital and late HIV diagnosis across race/ethnicity. AIM 2: To investigate mechanisms (HIV testing and HIV stigma) in relation to the association between social capital and late HIV diagnosis across race/ethnicity. AIM 3: To develop and pilot social capital indicators, tailored to HIV prevention. The candidate will develop additional training through didactic coursework in 1) advanced quantitative and qualitative research methods including spatial econometrics, ethnography, and community based participatory research; 2) epidemiologic/clinical study design, and 3) intervention development. The candidate will be mentored by a team of internationally renowned experts in HIV prevention research, social determinants of health, causal inference, and HIV surveillance systems. Mentor and advisory committee members are from Harvard University, City University of New York, Graduate School of Public Health and Health Policy, Emory University, and University of Pennsylvania. Institutional resources available to the candidate include Harvard Center for AIDS Research and The Fenway Institute. Findings from the proposed research will provide the competencies and preliminary data for the candidate to write an R01 or R34 proposal to develop, implement, and evaluate a community-level social capital-based HIV prevention intervention.